feat: Users, Diagnostics and Tuning sit on the admin layout like the rest: debug mode is a row action on Users, every admin load error has Try again, and figures carry their scale (M503 #5608)

- Users: a one-line count of accounts, admins and open invites; Turn on/off debug mode in each row's actions, and a "debug on" badge that opens that account's events
- Diagnostics: no title or paragraph of its own; devices named by account, OS, app version and last seen, not client id; opens on ?account=
- Tuning: each profile, the taste build and Discover are row groups with one-line hints; the sparkline has a 0–100% axis
- Requests, Duplicates, Missing files and Suspect sources: load errors offer Try again
- Library: cover art reads "N of M albums have art"

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/routes/admin/diagnostics/+page.svelte

@@ -1,5 +1,7 @@
 <script lang="ts">
   import { pageTitle } from '#lib/branding.js';
+  import { page } from '$app/state';
+  import { relativeTime } from '#lib/utils/relativeTime.js';
   import { Copy, Download, Activity } from 'lucide-svelte';
   import { useQueryClient } from '@tanstack/svelte-query';
   import {
@@ -49,8 +51,9 @@
   // start/end window is an Advanced affordance.
   const DEFAULT_LIMIT = 500;
 
-  // Filter state.
-  let accountId = $state('');
+  // Filter state. Users links here with ?account=<id> to open on that
+  // account's events (#5608).
+  let accountId = $state(page.url.searchParams.get('account') ?? '');
   let clientId = $state('');
   let kind = $state('');
   let fromLocal = $state('');
@@ -108,6 +111,12 @@
     return Number.isNaN(d.getTime()) ? iso : d.toLocaleString();
   }
 
+  // A device by what the operator knows it as, not its client id.
+  function deviceLabel(d: { username: string; os_version: string; app_version: string; last_seen: string; event_count: number }): string {
+    const parts = [d.username, d.os_version, d.app_version && `app ${d.app_version}`, `seen ${relativeTime(d.last_seen)}`];
+    return `${parts.filter(Boolean).join(' · ')} (${d.event_count} events)`;
+  }
+
   function payloadPreview(p: Record<string, unknown>): string {
     const s = JSON.stringify(p);
     return s.length > 120 ? s.slice(0, 120) + '…' : s;
@@ -122,10 +131,10 @@
       await updateUserDebugMode(selectedUser.id, !selectedUser.debug_mode_enabled);
       await client.invalidateQueries({ queryKey: qk.adminUsers() });
       pushToast(
-        `Debug mode ${selectedUser.debug_mode_enabled ? 'disabled' : 'enabled'} for ${selectedUser.username}`
+        `Debug mode ${selectedUser.debug_mode_enabled ? 'off' : 'on'} for ${selectedUser.username}.`
       );
     } catch (e: unknown) {
-      pushToast(`Toggle failed: ${errMessage(e)}`, 'error');
+      pushToast(`Debug mode not changed: ${errMessage(e)}`, 'error');
     } finally {
       toggling = false;
     }
@@ -176,24 +185,21 @@
 
 <svelte:head><title>{pageTitle('Admin · Diagnostics')}</title></svelte:head>
 
+<h2 class="sr-only">Diagnostics</h2>
+
 <div class="space-y-4">
-  <header>
-    <h1 class="font-display text-2xl font-medium text-text-primary">Device diagnostics</h1>
   <p class="text-sm text-text-secondary">
-      Enable debug mode on an account to have its device(s) stream a timeseries
-      of connectivity, UPnP-sync, and power/Doze events here. Filter to the
-      window you care about, then copy or download the slice for analysis.
+    Turn on debug mode for an account and its devices report connectivity, sync and power events
+    here, to copy or download.
   </p>
-  </header>
 
   <!-- Account debug-mode control -->
-  <section class="rounded-md border border-border p-3">
-    <div class="flex flex-wrap items-end gap-3">
+  <section class="flex flex-wrap items-end gap-3 rounded-lg border border-border bg-surface px-4 py-3">
     <label class="block text-xs text-text-secondary">
       Account
       <select
         bind:value={accountId}
-          class="mt-1 block w-56 rounded border border-border bg-surface px-2 py-1.5 text-sm text-text-primary"
+        class="mt-1 block w-56 rounded-md border border-border bg-background px-2 py-1.5 text-sm text-text-primary"
       >
         <option value="">All accounts</option>
         {#each users as u (u.id)}
@@ -201,23 +207,20 @@
         {/each}
       </select>
     </label>
-
     {#if selectedUser}
+      <span class="inline-flex items-center gap-1 text-sm text-text-secondary" data-testid="debug-state">
+        <Activity size={14} aria-hidden="true" />
+        {selectedUser.debug_mode_enabled ? 'Debug mode on: reporting' : 'Debug mode off'}
+      </span>
       <button
         type="button"
         onclick={toggleDebug}
         disabled={toggling}
-          class="rounded px-3 py-2 text-sm text-action-fg hover:opacity-90 disabled:opacity-50
-            {selectedUser.debug_mode_enabled ? 'bg-action-destructive' : 'bg-action-primary'}"
+        class="rounded-md border border-border px-3 py-1.5 text-sm text-text-secondary hover:bg-surface-hover hover:text-text-primary disabled:opacity-50"
       >
-          {selectedUser.debug_mode_enabled ? 'Disable debug mode' : 'Enable debug mode'}
+        {selectedUser.debug_mode_enabled ? 'Turn off' : 'Turn on'}
       </button>
-        <span class="inline-flex items-center gap-1 text-xs text-text-muted">
-          <Activity size={14} />
-          {selectedUser.debug_mode_enabled ? 'Reporting active' : 'Reporting off'}
-        </span>
     {/if}
-    </div>
   </section>
 
   <!-- Filters. Default view = most recent {DEFAULT_LIMIT} events, no time
@@ -232,7 +235,7 @@
         >
           <option value="">All devices</option>
           {#each devices as d (d.client_id)}
-            <option value={d.client_id}>{d.client_id.slice(0, 12)} · {d.event_count}</option>
+            <option value={d.client_id}>{deviceLabel(d)}</option>
           {/each}
         </select>
       </label>
@@ -325,7 +328,10 @@
 
   <!-- Timeline -->
   {#if diagQuery.isError}
-    <p class="text-error-fg">Couldn't load: {errMessage(diagQuery.error)}</p>
+    <p class="text-sm text-error-fg" data-testid="diagnostics-error">
+      Couldn't load the events: {errMessage(diagQuery.error)}
+      <button type="button" class="underline hover:no-underline" onclick={() => diagQuery.refetch()}>Try again</button>
+    </p>
   {:else if diagQuery.isPending}
     <p class="text-text-secondary">Loading…</p>
   {:else if rows.length === 0}

web/src/routes/admin/duplicates/+page.svelte

@@ -246,7 +246,10 @@
     {#if resolved.isPending}
       <p class="text-text-secondary">Loading…</p>
     {:else if resolved.isError && !resolved.isFetchNextPageError}
-      <p class="text-error-fg">Couldn't load what was resolved.</p>
+      <p class="text-sm text-error-fg">
+      Couldn't load what was resolved.
+      <button type="button" class="underline hover:no-underline" onclick={() => resolved.refetch()}>Try again</button>
+    </p>
     {:else if activity.length === 0}
       <div class="rounded-lg border border-border bg-surface p-6 text-center" data-testid="resolved-empty">
         <Copy size={28} strokeWidth={1} class="mx-auto text-text-muted" />
@@ -296,7 +299,10 @@
   {:else if query.isPending}
     <p class="text-text-secondary">Loading duplicates…</p>
   {:else if query.isError && !query.isFetchNextPageError}
-    <p class="text-error-fg">Couldn't load the duplicates report.</p>
+    <p class="text-sm text-error-fg">
+      Couldn't load the duplicates report.
+      <button type="button" class="underline hover:no-underline" onclick={() => query.refetch()}>Try again</button>
+    </p>
   {:else if groups.length === 0}
     <!-- Several states all show zero groups and mean different things. Telling
          them apart is what stops an empty page reading as a broken feature. -->

web/src/routes/admin/library/+page.svelte

@@ -175,7 +175,7 @@
       <SettingRow label="Covers" hint={coverage
         ? coverage.total === 0
           ? 'The library is empty.'
-          : `${n(coverage.with_art)} with art · ${n(coverage.pending)} still to look for · ${n(coverage.settled)} no source has`
+          : `${n(coverage.with_art)} of ${n(coverage.total)} albums have art · ${n(coverage.pending)} still to look for · ${n(coverage.settled)} no source has`
         : undefined}>
         <button type="button" onclick={onRefetchCovers} disabled={refetching} class={button}>
           {refetching ? 'Starting…' : 'Look for missing covers'}

web/src/routes/admin/library/library.test.ts

@@ -97,7 +97,7 @@ describe('Admin › Library', () => {
 
   test('cover art says how many have art, and can look for the missing and look again', async () => {
     setup();
-    expect(screen.getByText('90 with art · 6 still to look for · 4 no source has')).toBeInTheDocument();
+    expect(screen.getByText('90 of 100 albums have art · 6 still to look for · 4 no source has')).toBeInTheDocument();
     await fireEvent.click(screen.getByRole('button', { name: /look for missing covers/i }));
     await waitFor(() => expect(refetchMissingCovers).toHaveBeenCalled());
     await fireEvent.click(screen.getByRole('button', { name: /^look again$/i }));

web/src/routes/admin/missing-files/+page.svelte

@@ -87,7 +87,10 @@
   {#if query.isPending}
     <p class="text-text-secondary">Checking what's missing…</p>
   {:else if query.isError}
-    <p class="text-error-fg">Couldn't load the missing-files list.</p>
+    <p class="text-sm text-error-fg">
+      Couldn't load the missing files.
+      <button type="button" class="underline hover:no-underline" onclick={() => query.refetch()}>Try again</button>
+    </p>
   {:else if groups.length === 0}
     <!-- Empty state explains the feature, not just the emptiness: an operator
          who has never seen this page shouldn't have to guess what would put a

web/src/routes/admin/missing-files/missing-files.test.ts

@@ -123,7 +123,7 @@ describe('admin missing files', () => {
 
   test('shows an error line when the query fails', () => {
     renderWith(undefined, { isError: true });
-    expect(screen.getByText(/couldn't load the missing-files list/i)).toBeTruthy();
+    expect(screen.getByText(/couldn't load the missing files/i)).toBeTruthy();
   });
 
   // Not wanted yet is the common case for a folder that just went missing;

web/src/routes/admin/requests/+page.svelte

@@ -164,7 +164,10 @@
   {#if query.isPending}
     <p class="text-text-secondary">Reading the queue…</p>
   {:else if query.isError}
-    <p class="text-error-fg">Couldn't load requests.</p>
+    <p class="text-sm text-error-fg">
+      Couldn't load the requests.
+      <button type="button" class="underline hover:no-underline" onclick={() => query.refetch()}>Try again</button>
+    </p>
   {:else if rows.length === 0}
     <p class="text-text-secondary">Nothing here.</p>
   {:else}

web/src/routes/admin/suspect-sources/+page.svelte

@@ -110,7 +110,10 @@
   {#if query.isPending}
     <p class="text-text-secondary">Reading file names…</p>
   {:else if query.isError && !query.isFetchNextPageError}
-    <p class="text-error-fg">Couldn't load the suspect-sources list.</p>
+    <p class="text-sm text-error-fg">
+      Couldn't load the suspect sources.
+      <button type="button" class="underline hover:no-underline" onclick={() => query.refetch()}>Try again</button>
+    </p>
   {:else if groups.length === 0}
     <div class="rounded-lg border border-border bg-surface p-6 text-center">
       <FileCheck size={28} strokeWidth={1} class="mx-auto text-text-muted" />

web/src/routes/admin/tuning/+page.svelte

@@ -17,6 +17,8 @@
   } from '#lib/api/tuning.js';
   import { errMessage } from '#lib/api/errors.js';
   import { pushToast } from '#lib/stores/toast.svelte.js';
+  import SettingsGroup from '#lib/components/settings/SettingsGroup.svelte';
+  import SettingRow from '#lib/components/settings/SettingRow.svelte';
 
   // The defaults-discovery lab (#1250): DB-backed scoring-weight
   // profiles + taste-build knobs with live effect. This card exists to
@@ -26,38 +28,37 @@
   const weightFields: { key: keyof WeightProfile; label: string; hint: string }[] = [
     { key: 'base_weight',       label: 'Base weight',       hint: 'Floor score every candidate starts from.' },
     { key: 'like_boost',        label: 'Like boost',        hint: 'Added when the track is liked.' },
-    { key: 'recency_weight',    label: 'Recency weight',    hint: 'Rewards tracks not played recently (0–30d ramp).' },
-    { key: 'skip_penalty',      label: 'Skip penalty',      hint: 'Subtracts skips/plays ratio.' },
-    { key: 'jitter_magnitude',  label: 'Jitter',            hint: 'Random reshuffle magnitude for near-ties.' },
-    { key: 'context_weight',    label: 'Context weight',    hint: 'Session-vector similarity contribution.' },
-    { key: 'similarity_weight', label: 'Similarity weight', hint: 'Seed-similarity contribution.' },
-    { key: 'taste_weight',      label: 'Taste weight',      hint: 'Learned taste-profile fit, in [-1, +1].' },
-    { key: 'context_time_weight', label: 'Time-of-day weight', hint: "Artist's time-of-day/weekday affinity for the current context, in [-1, +1]. 0 = ignore when you listen." }
+    { key: 'recency_weight',    label: 'Recency weight',    hint: 'Rewards tracks not played in the last 30 days.' },
+    { key: 'skip_penalty',      label: 'Skip penalty',      hint: 'Subtracts the share of plays skipped.' },
+    { key: 'jitter_magnitude',  label: 'Jitter',            hint: 'Random shuffle among near-ties.' },
+    { key: 'context_weight',    label: 'Context weight',    hint: 'Fit with the current listening session.' },
+    { key: 'similarity_weight', label: 'Similarity weight', hint: 'Likeness to the seed.' },
+    { key: 'taste_weight',      label: 'Taste weight',      hint: 'Fit with the learned taste profile.' },
+    { key: 'context_time_weight', label: 'Time-of-day weight', hint: "Fit with when you usually play the artist. 0 ignores it." }
   ];
 
   const tasteFields: { key: keyof TasteTuning; label: string; hint: string }[] = [
-    { key: 'half_life_days',       label: 'Half-life (days)', hint: "A play's influence halves every this-many days." },
-    { key: 'engagement_hard_skip', label: 'Hard-skip point',  hint: 'Completion at/below which a play reads −1.' },
-    { key: 'engagement_neutral',   label: 'Neutral point',    hint: 'Completion at which a play reads 0.' },
-    { key: 'engagement_full',      label: 'Full point',       hint: 'Completion at/above which a play reads +1.' },
-    { key: 'enriched_tag_scale',   label: 'Enriched tag weight', hint: 'How much folksonomy tags (MusicBrainz/Last.fm) count vs raw file genre, in [0, 1]. 0 = genre only.' },
-    { key: 'era_scale',            label: 'Era weight', hint: 'How strongly a decade-play imprints on the era facet, in [0, 1]. 0 = era ignored.' },
-    { key: 'mood_scale',           label: 'Mood weight', hint: 'How strongly a mood-tagged play imprints on the mood facet (from folksonomy tags), in [0, 1]. 0 = mood ignored.' }
+    { key: 'half_life_days',       label: 'Half-life (days)', hint: "A play's influence halves every this many days." },
+    { key: 'engagement_hard_skip', label: 'Hard-skip point',  hint: 'Played this little or less reads as a dislike.' },
+    { key: 'engagement_neutral',   label: 'Neutral point',    hint: 'Played this far reads as neither.' },
+    { key: 'engagement_full',      label: 'Full point',       hint: 'Played this far or more reads as a like.' },
+    { key: 'enriched_tag_scale',   label: 'Enriched tag weight', hint: 'Style and mood tags against the file genre. 0 is genre only.' },
+    { key: 'era_scale',            label: 'Era weight', hint: 'How much the decade counts. 0 ignores it.' },
+    { key: 'mood_scale',           label: 'Mood weight', hint: 'How much the mood counts. 0 ignores it.' }
   ];
 
   const discoverFields: { key: keyof DiscoverTuning; label: string; hint: string }[] = [
-    { key: 'tag_overlap_weight', label: 'Taste-tag weight', hint: "How strongly a candidate's tags matching your taste boosts it. score x (1 + w x overlap), so 0 turns the tag term off and ranks on similarity alone. An artist with no cached tags is never penalised." },
-    { key: 'snooze_days',        label: 'Snooze length (days)', hint: 'How long "not right now" parks a suggestion before it returns on its own. Records no opinion about the artist and never feeds the taste profile.' }
+    { key: 'tag_overlap_weight', label: 'Taste-tag weight', hint: 'Boost for a suggestion whose tags fit your taste. 0 ranks on likeness alone.' },
+    { key: 'snooze_days',        label: 'Snooze length (days)', hint: 'How long "not right now" hides a suggestion.' }
   ];
 
   const profileScopes: { scope: WeightProfileScope; label: string; blurb: string }[] = [
-    { scope: 'radio', label: 'Radio', blurb: 'Seed-directed listening — the user picked a direction.' },
-    { scope: 'daily_mix', label: 'Daily mixes', blurb: 'For You, the discovery mixes, and "You might like".' },
+    { scope: 'radio', label: 'Radio', blurb: 'Listening that starts from a seed.' },
+    { scope: 'daily_mix', label: 'Daily mixes', blurb: 'For You, the discovery mixes and "You might like".' },
     {
       scope: 'songs_like',
       label: 'Songs like…',
-      blurb:
-        'The tightest surface: everything here should sound like the seed track. Similarity dominates on purpose — raising like/taste/recency here is what makes these mixes wander.'
+      blurb: 'Everything should sound like the seed; likeness leads on purpose.'
     }
   ];
 
@@ -83,7 +84,8 @@
     form = f;
   }
 
-  $effect(() => {
+  function loadTuning() {
+    loadFailed = false;
     getTuning()
       .then((snap) => {
         fillForm(snap);
@@ -92,7 +94,8 @@
       .catch(() => {
         loadFailed = true;
       });
-  });
+  }
+  $effect(loadTuning);
 
   // A knob deviates when its CURRENT SAVED value differs from shipped;
   // the dot marks where this install has drifted from defaults.
@@ -166,7 +169,8 @@
   let trends = $state<TrendsResponse | null>(null);
   let trendsFailed = $state(false);
 
-  $effect(() => {
+  function loadTrends() {
+    trendsFailed = false;
     getTrends()
       .then((t) => {
         trends = t;
@@ -174,10 +178,13 @@
       .catch(() => {
         trendsFailed = true;
       });
-  });
+  }
+  $effect(loadTrends);
 
   const SPARK_W = 220;
   const SPARK_H = 36;
+  // Room left of the plot for the y axis's 0% and 100%.
+  const GUTTER = 30;
   const TREND_LOW_VOLUME = 20;
 
   // The week axis is the sorted union of every series' buckets, so all
@@ -237,6 +244,10 @@
       : { skip: 0, completion: 0, plays: 0 };
   }
 
+  const button =
+    'rounded-md border border-border px-3 py-1.5 text-sm text-text-secondary hover:bg-surface-hover hover:text-text-primary disabled:opacity-50';
+  const primary = 'rounded-md bg-action-primary px-3 py-1.5 text-sm text-action-fg disabled:opacity-50';
+
   function pct(v: number): string {
     return `${(v * 100).toFixed(0)}%`;
   }
@@ -249,215 +260,109 @@
   }
 </script>
 
-<svelte:head>
-  <title>{pageTitle('Tuning')}</title>
-</svelte:head>
+<svelte:head><title>{pageTitle('Admin · Tuning')}</title></svelte:head>
 
-<div class="space-y-6 p-4">
-  <div>
-    <h1 class="text-xl font-semibold">Recommendation tuning</h1>
-    <p class="mt-1 max-w-3xl text-sm text-text-secondary">
-      The defaults-discovery lab. Changes apply live — radio on the next request, daily mixes on
-      the next rebuild — and every change is recorded so the metrics page can tie outcome shifts
-      to knob turns. Found-good values get baked into shipped defaults; a dot marks knobs that
-      currently deviate from them.
-    </p>
+<h2 class="sr-only">Tuning</h2>
+
+{#snippet knobs(scope: TuningScope, title: string, hint: string, fields: { key: string; label: string; hint: string }[], step: (key: string) => string, shipped: (key: string) => number)}
+  <SettingsGroup {title} {hint}>
+    {#each fields as f (f.key)}
+      <SettingRow label={f.label} for="{scope}-{f.key}" hint={f.hint}>
+        {#if deviates(scope, f.key)}
+          <span
+            class="inline-block h-1.5 w-1.5 rounded-full bg-accent"
+            title="Deviates from the shipped default ({shipped(f.key)})"
+          ><span class="sr-only">Changed from the default, {shipped(f.key)}</span></span>
+        {/if}
+        <input
+          id="{scope}-{f.key}"
+          type="number"
+          step={step(f.key)}
+          min={scope === 'discover' ? '0' : undefined}
+          bind:value={form[scope][f.key]}
+          class="w-24 rounded-md border border-border bg-background px-2 py-1.5 text-right text-sm tabular-nums"
+        />
+      </SettingRow>
+    {/each}
+    <div class="flex flex-wrap gap-2 px-4 py-3">
+      <button type="button" disabled={saving !== null} onclick={() => save(scope)} class={primary}>
+        Save {title.toLowerCase()}
+      </button>
+      <button
+        type="button"
+        disabled={saving !== null}
+        onclick={() => reset(scope)}
+        aria-label="Reset {title} to defaults"
+        class={button}
+      >
+        Reset to defaults
+      </button>
     </div>
+  </SettingsGroup>
+{/snippet}
+
+<div class="space-y-6">
+  <p class="text-sm text-text-secondary">
+    Scoring knobs that apply live, each change recorded against the trends below. A dot marks one
+    changed from the shipped default.
+  </p>
 
   {#if loadFailed}
-    <p class="text-sm text-text-secondary">Couldn't load tuning settings.</p>
+    <p class="text-sm text-error-fg" data-testid="tuning-error">
+      Couldn't load the tuning settings.
+      <button type="button" class="underline hover:no-underline" onclick={loadTuning}>Try again</button>
+    </p>
   {:else if !snapshot}
     <p class="text-sm text-text-secondary">Loading…</p>
   {:else}
-    <section class="grid gap-4 lg:grid-cols-2">
+    {@const snap = snapshot}
+    <div class="grid items-start gap-6 xl:grid-cols-2">
       {#each profileScopes as p (p.scope)}
-        <div class="space-y-3 rounded border border-border bg-surface p-4">
-          <div>
-            <h2 class="text-lg font-semibold">{p.label}</h2>
-            <p class="text-xs text-text-secondary">{p.blurb}</p>
-          </div>
-          <div class="space-y-2">
-            {#each weightFields as f (f.key)}
-              <div class="grid grid-cols-[1fr_7rem] items-center gap-2">
-                <label class="text-sm" for="{p.scope}-{f.key}" title={f.hint}>
-                  {f.label}
-                  {#if deviates(p.scope, f.key)}
-                    <span
-                      class="ml-1 inline-block h-1.5 w-1.5 rounded-full bg-accent align-middle"
-                      title="Deviates from the shipped default ({snapshot.shipped.profiles[p.scope][f.key]})"
-                    ></span>
-                  {/if}
-                </label>
-                <input
-                  id="{p.scope}-{f.key}"
-                  type="number"
-                  step="0.1"
-                  bind:value={form[p.scope][f.key]}
-                  class="w-full rounded border border-border bg-background px-2 py-1 text-right text-sm tabular-nums outline-hidden focus:border-accent"
-                />
-              </div>
+        {@render knobs(p.scope, p.label, p.blurb, weightFields, () => '0.1', (k) => snap.shipped.profiles[p.scope][k as keyof WeightProfile])}
       {/each}
+      {@render knobs(
+        'taste',
+        'Taste profile build',
+        'How plays become the taste profile. Keep dislike < neither < like.',
+        tasteFields,
+        (k) => (k === 'half_life_days' ? '1' : '0.05'),
+        (k) => snap.shipped.taste[k as keyof TasteTuning]
+      )}
+      {@render knobs(
+        'discover',
+        'Discover requests',
+        "How Discover ranks artists you don't have.",
+        discoverFields,
+        (k) => (k === 'snooze_days' ? '1' : '0.1'),
+        (k) => snap.shipped.discover[k as keyof DiscoverTuning]
+      )}
     </div>
-          <div class="flex gap-2">
-            <button
-              type="button"
-              disabled={saving !== null}
-              onclick={() => save(p.scope)}
-              class="rounded bg-accent px-3 py-1.5 text-sm text-white disabled:opacity-50"
-            >
-              Save {p.label.toLowerCase()}
-            </button>
-            <button
-              type="button"
-              disabled={saving !== null}
-              onclick={() => reset(p.scope)}
-              aria-label="Reset {p.label} to defaults"
-              class="rounded border border-border px-3 py-1.5 text-sm text-text-secondary hover:text-text-primary disabled:opacity-50"
-            >
-              Reset to defaults
-            </button>
-          </div>
-        </div>
-      {/each}
-    </section>
-
-    <section class="space-y-3 rounded border border-border bg-surface p-4 lg:max-w-xl">
-      <div>
-        <h2 class="text-lg font-semibold">Taste profile build</h2>
-        <p class="text-xs text-text-secondary">
-          How plays become the learned taste profile: the influence half-life and the
-          completion→engagement curve (must stay ordered: hard-skip &lt; neutral &lt; full).
-        </p>
-      </div>
-      <div class="space-y-2">
-        {#each tasteFields as f (f.key)}
-          <div class="grid grid-cols-[1fr_7rem] items-center gap-2">
-            <label class="text-sm" for="taste-{f.key}" title={f.hint}>
-              {f.label}
-              {#if deviates('taste', f.key)}
-                <span
-                  class="ml-1 inline-block h-1.5 w-1.5 rounded-full bg-accent align-middle"
-                  title="Deviates from the shipped default ({snapshot.shipped.taste[f.key]})"
-                ></span>
-              {/if}
-            </label>
-            <input
-              id="taste-{f.key}"
-              type="number"
-              step={f.key === 'half_life_days' ? '1' : '0.05'}
-              bind:value={form.taste[f.key]}
-              class="w-full rounded border border-border bg-background px-2 py-1 text-right text-sm tabular-nums outline-hidden focus:border-accent"
-            />
-          </div>
-        {/each}
-      </div>
-      <div class="flex gap-2">
-        <button
-          type="button"
-          disabled={saving !== null}
-          onclick={() => save('taste')}
-          class="rounded bg-accent px-3 py-1.5 text-sm text-white disabled:opacity-50"
-        >
-          Save taste
-        </button>
-        <button
-          type="button"
-          disabled={saving !== null}
-          onclick={() => reset('taste')}
-          aria-label="Reset taste profile build to defaults"
-          class="rounded border border-border px-3 py-1.5 text-sm text-text-secondary hover:text-text-primary disabled:opacity-50"
-        >
-          Reset to defaults
-        </button>
-      </div>
-    </section>
-
-    <!-- Discover request surface (#2377). Its own scope, not part of taste:
-         the snooze length lives here, and a snooze deliberately carries no
-         taste signal (#2374). -->
-    <section class="space-y-3 rounded border border-border bg-surface p-4 lg:max-w-xl">
-      <div>
-        <h2 class="text-lg font-semibold">Discover requests</h2>
-        <p class="text-xs text-text-secondary">
-          How the Discover suggestion deck ranks out-of-library artists. Tag coverage for
-          artists you don't own is partial by nature, so an untagged candidate keeps its
-          similarity score rather than being pushed down.
-        </p>
-      </div>
-      <div class="space-y-2">
-        {#each discoverFields as f (f.key)}
-          <div class="grid grid-cols-[1fr_7rem] items-center gap-2">
-            <label class="text-sm" for="discover-{f.key}" title={f.hint}>
-              {f.label}
-              {#if deviates('discover', f.key)}
-                <span
-                  class="ml-1 inline-block h-1.5 w-1.5 rounded-full bg-accent align-middle"
-                  title="Deviates from the shipped default ({snapshot.shipped.discover[f.key]})"
-                ></span>
-              {/if}
-            </label>
-            <input
-              id="discover-{f.key}"
-              type="number"
-              step={f.key === 'snooze_days' ? '1' : '0.1'}
-              min="0"
-              bind:value={form.discover[f.key]}
-              class="w-full rounded border border-border bg-background px-2 py-1 text-right text-sm tabular-nums outline-hidden focus:border-accent"
-            />
-          </div>
-        {/each}
-      </div>
-      <div class="flex gap-2">
-        <button
-          type="button"
-          disabled={saving !== null}
-          onclick={() => save('discover')}
-          class="rounded bg-accent px-3 py-1.5 text-sm text-white disabled:opacity-50"
-        >
-          Save discover
-        </button>
-        <button
-          type="button"
-          disabled={saving !== null}
-          onclick={() => reset('discover')}
-          aria-label="Reset discover requests to defaults"
-          class="rounded border border-border px-3 py-1.5 text-sm text-text-secondary hover:text-text-primary disabled:opacity-50"
-        >
-          Reset to defaults
-        </button>
-      </div>
-    </section>
   {/if}
 
-  <!-- Weekly trends (#1251): the verify half. Sparklines share one
-       week axis; dashed ticks mark knob turns so cause→effect reads
-       off the chart. -->
-  <section class="space-y-3 rounded border border-border bg-surface p-4">
-    <div>
-      <h2 class="text-lg font-semibold">Weekly trends</h2>
-      <p class="text-xs text-text-secondary">
-        Skip rate per surface over the last {trends?.weeks ?? 12} weeks (lower is better; all
-        users aggregated, rates only). Dashed ticks mark tuning changes. Taste hit is the share
-        of plays whose artist fits the current taste profile.
-        <span class="font-medium">The skip and completion columns show the most recent week
-        alone</span>, not the whole window — the figure after the skip rate is that week's
-        play count, so a rate drawn from a handful of listens reads as what it is.
-      </p>
-    </div>
+  <!-- Weekly trends (#1251): the verify half. Sparklines share one week
+       axis and a fixed 0–100% skip-rate axis; dashed ticks mark knob turns,
+       so cause and effect read off the chart. -->
+  <SettingsGroup
+    title="Weekly trends"
+    hint="Skip rate per surface, all listeners. Last-week columns carry that week's play count."
+  >
+    <div class="overflow-x-auto px-4 py-3">
       {#if trendsFailed}
-      <p class="text-sm text-text-secondary">Couldn't load trends.</p>
+        <p class="text-sm text-error-fg" data-testid="trends-error">
+          Couldn't load trends.
+          <button type="button" class="underline hover:no-underline" onclick={loadTrends}>Try again</button>
+        </p>
       {:else if !trends}
         <p class="text-sm text-text-secondary">Loading…</p>
       {:else if trends.series.length === 0}
-      <p class="text-sm text-text-secondary">
-        No plays recorded yet — trends appear once listening accumulates.
-      </p>
+        <p class="text-sm text-text-secondary">No plays recorded yet; trends appear once listening accumulates.</p>
       {:else}
+        {@const t = trends}
         <table class="w-full text-sm">
           <thead>
             <tr class="text-left text-text-secondary">
               <th class="py-1 font-medium">Surface</th>
-            <th class="py-1 font-medium">Skip rate by week</th>
+              <th class="py-1 font-medium">Skip rate, last {t.weeks} weeks</th>
               <th class="py-1 text-right font-medium">Plays<span class="font-normal text-xs"> (window)</span></th>
               <th class="py-1 text-right font-medium">Skip<span class="font-normal text-xs"> (last wk)</span></th>
               <th class="py-1 text-right font-medium">Completion<span class="font-normal text-xs"> (last wk)</span></th>
@@ -465,7 +370,7 @@
             </tr>
           </thead>
           <tbody>
-          {#each trends.series as s (s.key)}
+            {#each t.series as s (s.key)}
               <tr
                 class="border-t border-border"
                 class:opacity-60={s.plays < TREND_LOW_VOLUME}
@@ -476,16 +381,19 @@
                 <td class="py-1.5 pr-2">{s.label}</td>
                 <td class="py-1.5">
                   <svg
-                  width={SPARK_W}
+                    width={SPARK_W + GUTTER}
                     height={SPARK_H}
-                  viewBox="0 0 {SPARK_W} {SPARK_H}"
+                    viewBox="0 0 {SPARK_W + GUTTER} {SPARK_H}"
                     role="img"
-                  aria-label="{s.label} weekly skip rate"
+                    aria-label="{s.label} weekly skip rate, 0 to 100%"
                     data-testid="sparkline-{s.key}"
                   >
-                  <line x1="0" y1={SPARK_H - 0.5} x2={SPARK_W} y2={SPARK_H - 0.5}
-                        stroke="currentColor" opacity="0.15" />
-                  {#each trends.markers as m, i (i)}
+                    <text x={GUTTER - 4} y="7" text-anchor="end" font-size="8" fill="currentColor" opacity="0.6">100%</text>
+                    <text x={GUTTER - 4} y={SPARK_H - 1} text-anchor="end" font-size="8" fill="currentColor" opacity="0.6">0%</text>
+                    <g transform="translate({GUTTER},0)">
+                      <line x1="0" y1={SPARK_H - 0.5} x2={SPARK_W} y2={SPARK_H - 0.5} stroke="currentColor" opacity="0.15" />
+                      <line x1="0" y1="0.5" x2={SPARK_W} y2="0.5" stroke="currentColor" opacity="0.08" />
+                      {#each t.markers as m, i (i)}
                         <line
                           x1={markerX(m)} y1="0" x2={markerX(m)} y2={SPARK_H}
                           stroke="currentColor" opacity="0.35" stroke-dasharray="2,2"
@@ -494,21 +402,17 @@
                         </line>
                       {/each}
                       {#if s.points.length > 1}
-                    <polyline
-                      class="text-accent-fg"
-                      points={sparkPoints(s)}
-                      fill="none"
-                      stroke="currentColor"
-                      stroke-width="1.5"
-                    />
+                        <polyline class="text-accent-fg" points={sparkPoints(s)} fill="none" stroke="currentColor" stroke-width="1.5" />
                       {:else if s.points.length === 1}
                         <circle
                           class="text-accent-fg"
                           cx={xFor(s.points[0].week_start)}
                           cy={SPARK_H - s.points[0].skip_rate * SPARK_H}
-                      r="2" fill="currentColor"
+                          r="2"
+                          fill="currentColor"
                         />
                       {/if}
+                    </g>
                   </svg>
                 </td>
                 <td class="py-1.5 text-right tabular-nums">{s.plays}</td>
@@ -522,16 +426,17 @@
             {/each}
           </tbody>
         </table>
-      {#if trends.markers.length > 0}
-        <div class="space-y-1">
+        {#if t.markers.length > 0}
+          <div class="mt-3 space-y-1">
             <h3 class="text-sm font-medium">Tuning changes in this window</h3>
             <ul class="space-y-0.5 text-xs text-text-secondary">
-            {#each trends.markers as m, i (i)}
+              {#each t.markers as m, i (i)}
                 <li>{markerSummary(m)}</li>
               {/each}
             </ul>
           </div>
         {/if}
       {/if}
-  </section>
+    </div>
+  </SettingsGroup>
 </div>

web/src/routes/admin/users/+page.svelte

@@ -10,17 +10,18 @@
     deleteUser,
     resetUserPassword,
     updateUserAutoApprove,
+    updateUserDebugMode,
     createAdminUsersQuery,
     createAdminInvitesQuery,
     type AdminUser,
     type AdminInvite,
     type CreateUserInput
   } from '#lib/api/admin.js';
-  import { errCode } from '#lib/api/errors.js';
+  import { errCode, errMessage } from '#lib/api/errors.js';
   import { pushToast } from '#lib/stores/toast.svelte.js';
   import Modal from '#lib/components/Modal.svelte';
   import RowActionsMenu, { type RowAction } from '#lib/components/RowActionsMenu.svelte';
-  import { Shield, ShieldOff, CheckCircle2, XCircle, KeyRound, Trash2, Copy } from 'lucide-svelte';
+  import { Shield, ShieldOff, CheckCircle2, XCircle, KeyRound, Trash2, Copy, Bug, BugOff } from 'lucide-svelte';
 
   const client = useQueryClient();
 
@@ -163,6 +164,21 @@
     }
   }
 
+  // Debug mode makes the account's devices report diagnostics (#5608): a
+  // row action here, with the badge linking to that account's events.
+  async function onToggleDebug(u: AdminUser) {
+    saving = true;
+    try {
+      await updateUserDebugMode(u.id, !u.debug_mode_enabled);
+      await client.invalidateQueries({ queryKey: qk.adminUsers() });
+      pushToast(`Debug mode ${u.debug_mode_enabled ? 'off' : 'on'} for ${u.username}.`);
+    } catch (e: unknown) {
+      pushToast(`Debug mode not changed: ${errMessage(e)}`, 'error');
+    } finally {
+      saving = false;
+    }
+  }
+
   async function onGenerateInvite() {
     saving = true;
     try {
@@ -205,18 +221,22 @@
 
 <svelte:head><title>{pageTitle('Admin · Users')}</title></svelte:head>
 
+<h2 class="sr-only">Users</h2>
+
 <div class="space-y-8">
-  <header class="space-y-1">
-    <h2 class="font-display text-2xl font-medium text-text-primary">Users</h2>
-    <p class="text-text-secondary">
-      Manage user accounts and invites for this Minstrel instance.
+  {#if usersQuery.data}
+    {@const admins = users.filter((u) => u.is_admin).length}
+    <p class="text-sm text-text-secondary" data-testid="users-summary">
+      {users.length === 1 ? '1 account' : `${users.length} accounts`}, {admins === 1 ? '1 admin' : `${admins} admins`}{invitesQuery.data
+        ? ` · ${invites.length === 1 ? '1 invite open' : `${invites.length} invites open`}`
+        : ''}.
     </p>
-  </header>
+  {/if}
 
   <!-- Accounts section -->
   <section class="space-y-3">
     <div class="flex items-baseline justify-between">
-      <h3 class="font-display text-xl font-medium text-text-primary">Accounts</h3>
+      <h3 class="text-base font-medium text-text-primary">Accounts</h3>
       <button
         type="button"
         disabled={saving}
@@ -229,7 +249,10 @@
     {#if usersQuery.isPending}
       <p class="text-text-secondary">Reading users…</p>
     {:else if usersQuery.isError}
-      <p class="text-error-fg">Couldn't load users.</p>
+      <p class="text-sm text-error-fg" data-testid="users-error">
+        Couldn't load the accounts.
+        <button type="button" class="underline hover:no-underline" onclick={() => usersQuery.refetch()}>Try again</button>
+      </p>
     {:else if users.length === 0}
       <p class="text-text-secondary">No users yet.</p>
     {:else}
@@ -252,6 +275,15 @@
               onclick: () => onToggleAutoApprove(u),
               disabled: saving
             },
+            {
+              icon: u.debug_mode_enabled ? BugOff : Bug,
+              label: u.debug_mode_enabled ? 'Turn off debug mode' : 'Turn on debug mode',
+              ariaLabel: u.debug_mode_enabled
+                ? `Turn off debug mode for ${u.username}`
+                : `Turn on debug mode for ${u.username}`,
+              onclick: () => onToggleDebug(u),
+              disabled: saving
+            },
             {
               icon: KeyRound,
               label: 'Reset password',
@@ -278,6 +310,13 @@
                     data-testid="admin-badge"
                   >admin</span>
                 {/if}
+                {#if u.debug_mode_enabled}
+                  <a
+                    href="/admin/diagnostics?account={u.id}"
+                    class="inline-flex items-center rounded-full border border-border px-2 py-0.5 text-xs text-text-secondary hover:text-text-primary"
+                    data-testid="debug-badge"
+                  >debug on</a>
+                {/if}
                 {#if u.auto_approve_requests}
                   <span
                     class="inline-flex items-center rounded-full border border-border px-2 py-0.5 text-xs text-text-secondary"
@@ -301,7 +340,7 @@
   <!-- Invites section -->
   <section class="space-y-3">
     <div class="flex items-baseline justify-between">
-      <h3 class="font-display text-xl font-medium text-text-primary">Invites</h3>
+      <h3 class="text-base font-medium text-text-primary">Invites</h3>
       <button
         type="button"
         disabled={saving}
@@ -311,14 +350,14 @@
         Generate invite
       </button>
     </div>
-    <p class="text-sm text-text-secondary">
-      Invites expire after 24 hours and can be used once. Share the token with the
-      person you want to invite — they enter it on the registration page.
-    </p>
+    <p class="text-sm text-text-secondary">Each works once within 24 hours, entered on the sign-up page.</p>
     {#if invitesQuery.isPending}
       <p class="text-text-secondary">Reading invites…</p>
     {:else if invitesQuery.isError}
-      <p class="text-error-fg">Couldn't load invites.</p>
+      <p class="text-sm text-error-fg" data-testid="invites-error">
+        Couldn't load the invites.
+        <button type="button" class="underline hover:no-underline" onclick={() => invitesQuery.refetch()}>Try again</button>
+      </p>
     {:else if invites.length === 0}
       <p class="text-sm text-text-secondary">No active invites.</p>
     {:else}

web/src/routes/admin/users/users.test.ts

@@ -16,7 +16,8 @@ vi.mock('#lib/api/admin.js', () => ({
   createUser: vi.fn(),
   deleteUser: vi.fn(),
   resetUserPassword: vi.fn(),
-  updateUserAutoApprove: vi.fn()
+  updateUserAutoApprove: vi.fn(),
+  updateUserDebugMode: vi.fn()
 }));
 
 import AdminUsersPage from './+page.svelte';
@@ -29,7 +30,8 @@ import {
   createUser,
   deleteUser,
   resetUserPassword,
-  updateUserAutoApprove
+  updateUserAutoApprove,
+  updateUserDebugMode
 } from '#lib/api/admin.js';
 
 const alice: AdminUser = {
@@ -207,4 +209,30 @@ describe('/admin/users', () => {
     await fireEvent.click(screen.getAllByRole('button', { name: /Enable auto-approve/i })[0]);
     expect(updateUserAutoApprove).toHaveBeenCalledWith(expect.any(String), true);
   });
+
+  test('debug mode is a row action, and an account with it on links to its events', async () => {
+    (updateUserDebugMode as ReturnType<typeof vi.fn>).mockResolvedValue({});
+    setup([alice, { ...bob, debug_mode_enabled: true }]);
+    await fireEvent.click(screen.getAllByRole('button', { name: /turn on debug mode for alice/i })[0]);
+    expect(updateUserDebugMode).toHaveBeenCalledWith('u1', true);
+    expect(screen.getByTestId('debug-badge').getAttribute('href')).toBe('/admin/diagnostics?account=u2');
+  });
+
+  test('the page opens with how many accounts, admins and open invites there are', () => {
+    setup([alice, bob], [sampleInvite]);
+    expect(screen.getByTestId('users-summary').textContent?.replace(/\s+/g, ' ').trim()).toBe(
+      '2 accounts, 1 admin · 1 invite open.'
+    );
+  });
+
+  test('accounts that fail to load say so, with Try again', async () => {
+    const refetch = vi.fn();
+    (createAdminUsersQuery as ReturnType<typeof vi.fn>).mockReturnValue(
+      mockQuery({ isError: true, error: new Error('x'), refetch })
+    );
+    (createAdminInvitesQuery as ReturnType<typeof vi.fn>).mockReturnValue(mockQuery({ data: [] }));
+    render(AdminUsersPage);
+    await fireEvent.click(screen.getByRole('button', { name: /try again/i }));
+    expect(refetch).toHaveBeenCalled();
+  });
 });